The Drillers’ View

RGawthorpe@ECORD_IODP_DSC04635 copy

The ADs describe their working day

A typical day for the Day Shift will start with a Toolbox Meeting in the Conference Room at 11:30am.

After the Toolbox we will make our way to the Doghouse for a Handover from the Night shift. This will consist of the drillers having a separate Handover in regards to the hole and how it’s drilling.

The ADs (Assistant Drillers) will handover if there’s any Equipment Isolations or Permits to Work open and if so describe the nature of the work. The Night Shift will also inform us of any maintenance they have performed on equipment or breakdowns they have encountered.

So during drilling operations the ADs will carry out maintenance, mix mud and generally help out anyone requiring assistance in between core runs.

Our main areas of responsibility are to mix mud, operate the PDPH (Pipedeck Pipehandler) and TFM (Tubular Feeding Machine) and Tool Handling when recovering core samples.

Mixing Mud

DSmith@ECORD_IODP (143)

 

Using the sophisticated mud system on board we, at request of the driller, have various viscosity muds readily available depending on the ground the driller is coring through. This product clears waste material, called “cuttings” away, or is used to stabilize the hole.

“Mud” is a mixture of fresh water and a clay product called Bentonite or other additives depending on the type of drilling in progress. It is mixed with fresh water to increase dispersion into any unstable layers. We can also change the viscosity. So a thicker mud is used for sand layers where the ground is less stable where a thinner mix would simply disperse into the ground providing no support. We measure the viscosity using a beaker and funnel, timing how long it takes to reach a certain level.

Current situation

We are drilling through clay layers and the hole is stable so sea water is being pumped down the “String” to clear the cuttings away. The drill pipe in the hole is referred to as the “String”.

So far maintenance-wise the ADs have checked that the mud pumps are running smoothly and the mud stored in the tanks is agitated so as the product does not separate.

We will be performing a Derrick sweep later in the day to make sure systems housed within are all functioning. This consists of greasing sheaves, physically checking fixings and secondary retentions and checking for corrosion to the structure. Also a good time to take in the stunning views of the Gulf.

We now await the arrival of a fresh core sample to be winched up where we will strip the core barrel, extract the sample and rebuild the barrel to send back for another core run.

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The Raffle Candy Hat

The Science Party have a slightly different take on the idea of Advent this year. Christmas started remarkably early. The Thanksgiving decorations came down on the 25th of November

and five minutes later strings of fairy lights, baubles and tinsel appeared from nowhere. Tools were downed for the next half an hour, and to the melodic strains of Bing Crosby our containers were hung with the finest decorations to be found anywhere on the Gulf of Corinth.

The Advent Calendar hangs in the Curation Container. It’s a special one, full of Swiss chocolate balls (you know the brand), and strangely became the subject of some debate. When should we start opening it? If we waited until the 1st of December, then there would be (hopefully!) six doors still waiting to be opened when we finally disembark the ship at the end of the job. This caused some serious consternation amongst some of the more confectionary-oriented members of the SP. This could not be allowed to happen! All of the chocolate must be eaten! None can be left!

So hang on…. In theory it’s 24 days from today to the end of the Expedition. BOOM! Quickly decorate a hard hat, print everyones names out and put them in our new Christmas “Raffle Candy Hat” (thanks Patrizia!) and we’re ready to draw for the first chocolate ball. All we need to watch out for is Erwan sneaking extra copies of his name in. Again.

Believe me. These things are important…

Happy Thanksgiving!

Happy Thanksgiving from Expedition 381 on the Gulf of Corinth!

To celebrate Thanksgiving we would like to share what everyone is most thankful for.

The answers were:
“Bacon”
“Coffee”
“Comfortable Beds”
“Daily Dolphin Show”
“Family”
“Green Mud”
“Happy Science and ESO Team”
“Internet”
“Rainbows and Unicorns”
“Rioja”
“Sea sickness patches”
“Strong Coffee”
“Team Effort”
“Thanksgiving with “All’ Ya’ll””
“The lovely people onboard”
“The opportunity to be on the expedition”
We miss all friends and family and wish you safe and happy holidays!

From all Expedition 381 participants!

(List compiled by Clint Miller, Exp.381 geochemist)

 

Why are we here? Plate tectonics and the Gulf of Corinth

You may have wondered why we are drilling and sampling the sediments in this beautiful part of central Greece. The Gulf of Corinth is part of a continental rift system – where a tectonic plate is pulled apart and stretched. This is the first stage in the process that ultimately forms our oceans and ocean basins, such as the Atlantic Ocean, and has shaped the Earth’s surface that we know today. The rifting process causes the Earth’s crust and lithosphere to stretch and thin and the surface to subside. In the upper part of the crust the stretching and subsidence is taken up by fault structures which move during earthquakes every few hundred years. This creates a hole or basin which fills with sediments and water. In the Gulf we have up to 2.5 km of sediment and nearly 1 km of water. The Corinth Rift is only in the very first stage of rifting – where we are drilling, rifting only started about 1 or 2 million years ago. That may seem long for the non-geologist but is a fraction of the time it takes to form an ocean basin.

Cartoon

The reason we are working in this part of Greece is to understand the first stage of this process which is very well preserved here, particularly in the deep sea sediments of the Gulf of Corinth. By sampling the sediments we can determine their age, and from that we can tell how fast the faults slip, and when and how fast the basin opened and subsided. Knowing how fast the faults are moving will also help us understand better their earthquake-generating potential in this very seismically active region. We can also see how basin formation and the climate of the area caused sediments to be eroded and transported into the basin.

If you are interested in learning how the environment of the basin changed, please also take a look at the post from Clint Miller on “Sea Level Change” which tells you about how the basin has been affected by sea level change and tectonics. Also take a look at the post from Rob Gawthorpe “Onshore from the Offshore Perspective” to see how the rift faults have affected the shores of the Gulf of Corinth.

Lisa McNeill

Images:

View east along the southern shore of the Gulf of Corinth, near Aigion, showing the topographic effects of the rift faulting. The hills to the right are uplifted whilst the Gulf to the left subsides.

Cartoon showing how the Earth’s lithosphere (the tectonic plate) and the crust thin during stretching. The upper crustal stretching is generated by movement on faults. The fault movement and crustal thinning cause subsidence which create the water and sediment filled basin of the Gulf of Corinth.

Sea level change – signs in the sediments

How does sea level change affect marine life? This is one intriguing question Expedition 381 is exploring. We know sea level rises and falls around 120 meters (~400 feet) every time the planet alternates between glacial and interglacial periods. Scientists use the term glacial to describe intervals when the Northern Hemisphere had large ice sheets extending well into Canada, United States, and much of Europe. As ice built up it took water from the ocean lowering the average sea level of the planet. The Gulf of Corinth is an ideal location to study the rise and fall of sea level because the entrance (Rion sill) is only 61 meters below sea level. Therefore, the Gulf of Corinth was sometimes connected to the Mediterranean and at other times it was an isolated lake!

Of course, seawater and lakes have very different animals and plants. Also, oceans have distinctive chemistry compared to freshwater. These differences will cause changes in the geology which we can observe in the drilled cores. Many of the records we are collecting show these variations clearly! As we drill in different locations and measure different aspects of the sediment and pore water, we learn the fine details of these processes.

As all fun science however, the more we learn the more questions we create!

Clint Miller

Main image: Simone Sauer and Patrizia Geprägs collecting methane samples. Courtesy of DSmith@ECORD/IODP

Cores, Coffee and Food!!

From the first few weeks of the expedition offshore, three priorities have emerged within the team. In no particular order; Cores, Coffee and Food! We’ve focussed on the cores previously so this one is about the coffee and food!

We started off well with a gift of ‘Γιαννιώτικα βανίλιας’ (vanilla butter biscuits) and ‘Πιπερόπιτα’ (pepper pie), from the family of our Greek ESO team member, Apos, when we left Corinth. These were gratefully received and kept the team going for a few days!

We also have a number of coffee making options and paraphernalia in the containers, with the kettle on a near constant boil. The first few hours of each shift see many coffees consumed, while productivity ramps up!

Meals are provided on the ship every 6 hours. This means at breakfast time for one shift, the other shift are eating their evening meal. The 5am breakfast meal is eagerly awaited on the night shift (we try not to think so much about how many eggs we are consuming!) whilst the day shift looks forward to a 5pm feast. We are well fed and treated to Fajita Friday and Steak Saturday.

In between times there are biscuits, chocolate and snacks which emerge periodically, often from the snack drawer in the Science container!

Sophie Green

Images courtesy of ATsilligiannis@ECORD/IODP and SGreen@ECORD/IODP

Core Flow

After the cores arrive on deck (as described in Dave’s drilling blog), they are greeted by a squad of expectant Scientists. Offshore, we measure ephemeral properties from whole cores and samples taken from the core catchers, and store the cores in refrigerated containers called “reefers”. These data will help inform the sampling plan when the cores are split at the Bremen Core Repository early next year.

The first samples are taken on the curation table, located on the drilling deck. After the cores have been cut into sections, the Geochemists take samples from the cleanly cut ends for later measurement of methane concentration. We also have a handheld penetrometer device which is used to give an idea of the stiffness of the material.

The core then starts its journey down the street of containerised laboratories on the back deck. First stop is the curation container. Here, core measurements are taken and recorded – what was the drilled length, what was the length of recovered core, date, time and unique core section number. Samples from the core catchers are also taken to be analysed for microfossils and sedimentology. Further samples are taken on some cores to extract pore water When extracted the water is taken to the Geochemistry container for preliminary measurements (of pH, alkalinity, salinity and ammonium) and preservation for future use.

The next stop is the Multi Sensor Core Logger (MSCL) container. Here physical properties of the whole round cores are measured through the plastic liners. The cores are placed on a track and run through sensors to measure density, p-wave velocity, electrical resistivity, magnetic susceptibility and natural gamma radiation. We can use these data, alongside the other preliminary measurements, to understand how environments change as we move down and hole, and back in time.

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Finally the cores make it to the Science Office! In here the Sedimentologist on shift will examine both the core catcher samples and what they can see through the liners. Although the liners are clear, the view can be obscured by mud, and many features will not be visible until we get to Bremen next year and split the cores. The Micropaleontologists also sit in this space and use microscopes to identify microfossils which can give us an idea on the age of the sediments and the environment in which they formed. Also in this container are the Co-Chief Scientists, Lisa and Donna, who work on integrating existing data with our new cores and trying to understand the changes we see, using the various streams of evidence from all these measurements.

The cores finally come to rest in the reefers. At the end of the offshore phase of Expedition 381 they’ll travel on to the IODP Bremen Core Repository, MARUM Germany, to be met by the whole Science Party at the end of January, where the cores will be split and the detailed analyses undertaken.

Sophie Green

Images courtesy of CMiller@ECORD_IODP; SSauer@ECORD_IODP; DSmith@ECORD_IODP and ELeBer@ECORD_IODP